OBJECTIVE: To determine if significant radiation savings can be effected by using ultrafast screen/film systems or whether excessive repeat rates in conjunction with possible reduction in image quality and user problems may make ultrafast systems unacceptable. METHODS: Hospital study: We have completed an extensive field study (85,000 cases) using an ultrafast combination and now re-equipping with slower calcium tungstate screens. We will collect data on exposure levels, numbers of films used, repetition rate, and cumulative patient surface area imaged, from which the radiation "emitted" by the department over one year will be calculated (R/square cm) and compared with the previous study to quantitate the amount of radiation saved. Subjective assessments of image quality will be obtained. Laboratory study: We will calculate the degree of non-linearity of response to kV for ultrafast and conventional s/f combinations - develop and measure the relative latitudes of the two systems - measure the degree of reciprocity failure of the fast system - develop a "fixed kV varying mA" technique chart for the ultrafast combination and measure radiation reduction using a very low radioabsorptive input surface for the cassette.